Reaction Engines Ltd believes its novel Sabre engine, which would operate like a jet engine in the atmosphere and a rocket in space, could displace rockets for space access and transform air travel by bringing any destination on earth to no more than four hours away.

That ambition was given a boost on Wednesday by ESA, which has acted as an independent auditor on the Sabre test programme.

"ESA are satisfied that the tests demonstrate the technology required for the Sabre engine development," the agency's head of propulsion engineering Mark Ford told a news conference.

"One of the major obstacles to a re-usable vehicle has been removed," he said. "The gateway is now open to move beyond the jet age."

The space plane, dubbed Skylon, only exists on paper. What the company has right now is a remarkable heat exchanger that is able to cool air sucked into the engine at high speed from 1,000 degrees Celsius to minus 150 degrees in one hundredth of a second.

That ambition was given a boost on Wednesday by ESA, which has acted as an independent auditor on the Sabre test programme.

lol I like what you did there, but if it works as a Jet, (ie, it's taking in air) how will it work as a rocket (at least in outer space terms, where it'll need it's own combustion medium?) the shape of the thing I would imagine would be peculiar at best, probably not even aerodynamyc (however it is spelled)

Skylon's engine is a combined cycle rocket - carrying liquid oxygen for use in space and extracting/chilling liquid air in the atmosphere. In both stages of flight the fuel is liquid hydrogen.

All this based on known, if advanced, engineering principles. The big "IF" was the precooler, which is to take in superhot air and liquify it on the fly, and that was successfully tested this summer. That precooler will have lots of uses besides Skylon.

Skylon's engine is a combined cycle rocket - carrying liquid oxygen for use in space and extracting/chilling liquid air in the atmosphere. In both stages of flight the fuel is liquid hydrogen.

All this based on known, if advanced, engineering principles. The big "IF" was the precooler, which is to take in superhot air and liquify it on the fly, and that was successfully tested this summer. That precooler will have lots of uses besides Skylon.

Ok, and thanks, I was wondering how they would get it to work in a vacuum

I agree! I've always hated it when my General Electric F119 turbojet-powered (35,000 lb. thrust, w/ thrust vectoring technology) La-Z-Boy recliner would flame out above 80,000 feet due to lack of oxygen. Super-cruise was, of course, available below those altitudes, but this new technology will solve a lot of my current problems...

Don't get too enthusiastic - Skylon is a medium lift launcher so heavy stuff is out for it. That said, thd precooler could also be used to up the engine performance of straight turbojets for supersonic transports.